High costs of aircraft operation and desires on the part of governmental agencies to efficiently and effectively train aircraft pilots have resulted in efforts to develop cost effective flight simulator apparatus. The United States Federal Aviation Administration has recently implemented an advanced flight simulation program requiring that flight simulators accurately depict an aircraft's performance on take-off and landing maneuvers as well as on the ground, provide an improved visual response time and increased fields of vision, and provide daylight capabilities plus adverse weather features to allow pilots to upgrade from co-pilot to captain on the same aircraft or to laterally transfer crew members from one aircraft type to another entirely in a simulator.
With operating costs of large jet liners such as a Boeing 747 running $6,500 to $7,000 per hour, commercial carriers and the military alike are interested in lower cost flight simulators for providing total simulation training. Flight simulation apparatus employing high-speed supercomputers and superminicomputers to create graphics displays in real time have been developed in response to this need. Costs of many current flight simulation apparatus are around $250-300 per hour due to the high computational cost of generating realistic real-time images for the flight simulators which can be reproduced rapidly enough to be convincingly realistic. Costs of this order, however, are prohibitive for smaller commercial and private carriers and private pilots, who must still rely upon actual flight time for training and upgrading. Moreover, the resolution of the graphics displays of many of these systems leaves much to be desired when the computer-generated images are created at rates high enough to avoid perceptible flicker. Accordingly, there is a need for a means of producing convincingly realistic images for flight simulators at drastically reduced costs which do not involve the real-time generation of sophisticated realistic computer graphics by supercomputers and superminicomputers.
Recent advances in interactive video disc playback devices have provided hope that these devices can be successfully employed in flight simulation. One typical interactive video playback device is shown in U.S. Pat. No. 4,449,198 to Kroon et al. This patent illustrates an interactive video playback device wherein stored video and audio information may be accessed under the control of selection signals received from a computer. Each video frame includes a frame number which is supplied to the computer and allows an operator to activate a branching or selection between frames.
One problem with randomly addressable interactive video discs such as described in the aforementioned patent is that there is no provision for realistically connecting sequences of images so as to provide the illusion of true freedom of movement. Such interactive video disc devices are substantially sequential memory devices not unlike common phonograph records. If an operator wishes to play a different song (the analog of selecting a different sequence of images to simulate movement in a different direction), the needle must be picked up and moved to another portion of the disc.
The extent to which a playback apparatus for a video disc can be moved to another location on the video disc without experiencing information interruption is limited by the amount of buffering the system designer is willing to incorporate and the access time it takes the playback apparatus to move from one portion of a video disc to another. In one popular interactive video disc game known as "Dragon's Lair", the operator is frequently presented with a blank screen and a pause in playback while the system searches for the next sequence of images on the video disc which should follow as a result of operator input. It is apparent that such pauses and screen blankings are unacceptable if truly realistic flight simulation or other simulation of movement within three-dimensional space is to be provided.
One of the main reasons that commercially available video disc players have met only limited success in flight simulation and other random access applications is that most of these devices have but a limited ability to jump or skip tracks on the video disc. One prior art system, known as the model LD-V1000 manufactured by Pioneer Electronics (U.S.A.), Inc., embodies a technique for selectably retrieving video information from any of a plurality of information tracks by deflecting a mirror to reflect a laser beam radially relative to the disc. A laser beam/mirror deflection system such as shown in U.S. Pat. Nos. 3,944,727; 4,451,913; 4,282,598; 3,914,541; and 3,829,622 is employed to scan the beam across a predetermined number of tracks. The number of tracks across which the beam can be scanned is limited by the field of view of the deflecting mirror and the speed and extent to which the mirror can be deflected, and the optics which detect the reflected beam.
The deflecting mirror in the above-described prior art apparatus is physically mounted to a slide mechanism, which translates in a radial direction with respect to the video disc. Servomechanism circuitry and motors are provided for deflecting the mirror between extremes when a multiple track jump is desired, and for actuating the slide to move the mirror toward the jump direction. When a jump is desired, the deflecting mirror, which is lightweight and can be actuated extremely rapidly, is first moved to an extent corresponding to the size of the jump. The slide servomechanism, being far heavier and possessing much greater inertia, also begins accelerating, albeit at a slower rate, to "catch up" with the deflected laser beam, in order to recenter the deflecting mirror into the center of its field of view.
The above-described prior art laser beam/mirror deflecting system has proven to be unreliable in accurately jumping more than about one hundred tracks. In order to successfully implement an apparatus for simulating freedom of movement within a multi-dimensional space, it is necessary to reliably randomly access as many tracks as possible. The laser beam/mirror system is believed to be the best available at present, but still suffers from the disadvantage that it is configured to provide jumps in one direction only in increments of ten, for a maximum of about one hundred tracks. The apparatus can only jump in the reverse direction one track at a time, thereby severely limiting the rate at which random seeks can be accomplished in the reverse direction. The "search" mode in this apparatus also possesses the undesirable characteristic that a jump greater than one hundred tracks results in a blank video signal while the proper track number is sought.
Accordingly, in order to successfully implement a method and apparatus for simulating freedom of movement within a multi-dimensional space employing a video disc playback apparatus, these and other problems in effectuating accurate and reliable jumps over multiple tracks must be overcome.
Recent advances in generating realistic graphic images by computer have made it desirable to incorporate new techniques into flight simulation. Although costs of the computers and software for generating realistic computer images are falling rapidly, the computational demands of realistic image creation are immense. Typically, supercomputers such as a Cray X-MP Super Computer, manufactured by Cray Research, can perform over 400 million mathematical computations per second, but even such a supercomputer can produce only around 25 minutes of high quality 70-millimeter computer-generated film images per month. Fast minicomputers can produce an average of only about 2.5 minutes of 70-millimeter film per year. While it is desirable to use newer image synthesis techniques such as fractal geometry for generating images for flight simulation and other applications such as games, it is presently difficult if not impossible to generate and display such images in real time. Accordingly, there is a need for creating highly realistic images off-line, and providing for storage and retrieval of previously-generated images for applications such as flight simulators and games without screen blanking and pauses.